High Aspect Ratio Vias Filled with Liquid Metal Fill

This is a continuation of U.S. patent application Ser. No. 18/554,556 filed Oct. 9, 2023, which is the National Stage Application of International Patent Application No. PCT/US2022/024275, filed Apr. 11, 2022, which claims priority to U.S. Patent Application Ser. No. 63/173,135 filed Apr. 9, 2021, U.S. Patent Application Ser. No. 63/211,330 filed Jun. 16, 2021, and U.S. Patent Application Ser. No. 63/301,425 filed Jan. 20, 2022, the disclosure of each of which is hereby incorporated by reference as if set forth in its entirety herein.

Embodiments described herein generally relate to filling vias in a substrate.

Thin glass or optically transparent dielectric substrates, such as fused silica/quartz, crystalline silicon, borosilicate, sapphire, or other dielectric substrates are created having a plurality of metallized vias that are metalized in such a manner as to create an electrical path. In the case of through vias, the electrical path extends from a first surface of the substrate to a second surface that can be opposite the first surface. The integrated circuit packaging industry refers to these substrates as interposers that can define electrical connections at opposed ends of the electrical vias. Vias fabricated into the interposer are typically very small, for example, from 5 μm to 100 μm in diameter and from 50 μm to 500 μm in depth from the first surface to the second surface. The number of vias per square centimeter may be in the hundreds or even thousands. Following the processing necessary to fabricate these vias the next step is to metalize the vias to provide for an electrically conductive pathway from one circuit plane or substrate to another.

Electrically conductive vias can be filed by copper (Cu) plating or electrically conductive pastes that contain Cu, glass frit, or both. Other approaches include introducing a molten metal into the substrate. However, such approaches include a protective layer on the substrate, thereby adding cost and complexity to the manufacturing process, and also producing a two-piece substrate structure.

Approaches for filling glass vias are described in U.S. Pat. No. 7,276,787, PCT Publication No. WO 2021/067330, U.S. Pat. Nos. 4,412,642, and 6,294,745, the disclosure of each of which is hereby incorporated by reference as if set forth in its entirety herein.

What is needed is an improved method for metallizing vias of a substrate, and the resulting substrates having metallized vias.

In accordance with one example, a molten metal can at least partially fill empty or hollow vias of a substrate that extend at least into or through the substrate. The molten metal can fill at least approximately 30%, at least approximately 40%, at least approximately 50%, at least approximately 60%, at least approximately 70%, at least approximately 80%, at least approximately 90% or at least approximately 95% of the respective volumes of the vias. The metal can be a pure metal or can be a metal alloy as desired.

Thus, a method to produce a substrate with at least one via that is filled can include a step of filing, at least 30% to at least 95% of a volume of an unfiled via with a liquid metal or a molten metal. A method to produce a substrate with a molten metal-filled via can include a step of changing a contact angle of the substrate, with respect to the molten metal, to less than 90 degrees. A method to produce a substrate having a molten metal filled via can include a step of wetting an interior via sidewall of the via prior to adding molten metal or molten metal alloy into the via or into an unfilled volume of the via.

A method to produce a filled via substrate can include a step of providing a substrate that has a first melt or transition temperature and that defines at least one via. The method can further include a step of wetting an interior via sidewall of the at least one via with an adhesion liner. The method can further include a step of wetting any one or both of a first via opening and a second via opening opposed to the first via opening with the adhesion liner. The method can further include a step of adding an additional electrically conductive second layer on top of or over the adhesion liner. The method can further include a step of pre-heating the substrate. The method can further include a step of spraying or applying solder flux onto a first surface of the substrate. The method can further include a step of dipping or submerging the substrate into a bath of molten metal or a molten metal alloy, wherein the molten metal or molten metal alloy is at a second melt or liquid phase temperature that is numerically less than the first melt or transition temperature.

A substrate can include a first material with a first melting or transition temperature and at least one via. The at least one via can be filled with an electrically conductive material that flowed into the at least one via in a heated liquid or molten state. An unoccupied void in the at least one via can be filled with an electrically conductive material that flowed into the at least one via in a heated, liquid or molten state.

A substrate can include a first material with a first melt or transition temperature and at least one via. The at least one via can include a copper deposition, in addition to a fluid or heated or molten metal or metal alloy that entered into the at least one via by capillary action.

A substrate can include a first material with a first melt or transition temperature and at least one via. The at least one via can be filled at least 50% with a molten, electrically conductive material.

A substrate can include a first material with a first melt or transition temperature and at least one via. The at least one via can contain both a deposited electrically conductive material, such as one or both of an adhesion liner and a second layer, and a poured or molten or heated metal or metal alloy having a second liquid phase temperature that is less than the first melt or transition temperature.

A substrate can include a first material that defines at least one via, and a solid, continuous column of an electrically conductive material that (i) extends from a first via opening to an opposed second via opening and (ii) entered into the first via opening in a liquid state, and perhaps by capillary action.

A substrate can include a first material that defines at least one via having a length and a diameter. An aspect ratio of the length of the at least one via to the diameter of the at least one via can be at least approximately five. A cooled molten metal or metal alloy can fill at least 30% of the at least one via.

A substrate can include a metal preform or a preformed metal that is subsequently reflowed into a via defined in the substrate. The substrate can be a glass substrate, such as borosilicate, fused silica/quartz, sapphire, etc.

The above and other features, elements, characteristics, steps, and advantages of the present invention will become more apparent from the following detailed description of the embodiments of the present invention with reference to the attached drawings.

Referring initially to, an electrically conductive substratecan be configured for anatomical implantation, and is thus biocompatible. In one example, the electrically conductive substratecan be configured as an interposer that is configured to establish electrical connection between a pair of electrical devices. The electrically conductive substratecan include a monolithic substrate body. The substrate body, and thus the substrate, can define an external first outer surfaceand an external second outer surfacethat is opposite the first outer surface. The electrically conductive substratecan further include at least one viathat extends from a first endto a second endopposite the first end. The viacan extend through the substrate bodyfrom at least one of the first and second surfacesandtoward or to the other of the first and second surfacesand. Thus a first openingof the viacan be defined in the first outer surface. A second openingof the viacan be defined in the second outer surface. In one example, the viacan be configured as a through via (TV) that extends from the first outer surfaceto the second outer surface. It should be appreciated, of course, that the viacan be configured in any suitable alternative manner as desired, such as a blind via having only a single opening to an outer surface of the substrate body. The substrate bodycan define at least one inner surfacethat defines the via. The inner surfacecan extend from one of the first and second surfacesandtoward the other of the first and second surfacesand. For instance, the inner surfacecan extend from the first surfaceto the second surface.

The substrate bodycan be a monolithic substrate body, meaning that the substrate bodycan be homogenous from the first outer surfaceto the second outer surface. The substrate bodycan be made from any suitable material as desired, having a material transition temperature. The material can soften at the material transition temperature. The material can further define a material melting temperature at which the material melts. The material melting temperature can be higher than the material transition temperature. In one example, the material can be glass, such that the material transition temperature can be a glass transition temperature. In one example, the glass can be an optically transparent glass. The glass can be a borosilicate, fused silica/quartz, sapphire, or any suitable alternative glass material as desired. In some examples, the first and second outer surfacesandof the substrate bodyalso define the first and second outer surfaces of the substrate. Thus, in some examples the substrate bodydoes not support a protective layer or sacrificial layer on either of the first and second outer surfacesandboth during fabrication of the substrateand after fabrication of the substrate. Further, in some examples the substrate bodydoes not support a non-glass protective layer or sacrificial layer on either of the first and second outer surfacesandboth during fabrication of the substrateand after fabrication of the substrate.

The viacan include a metalthat can be in a solidified state so as to define a solid or solidified metal. The solidified metalcan extend continuously between the first surfaceand the second surfaceso as to define an electrically conductive path between the first surfaceand the second surface. In one example, the solidified metalcan extend continuously from the first surfaceto the second surface. Thus, the solidified metalcan define an electrically conductive path from the first surfaceto the second surface. In some examples, the solidified metaldoes not extend beyond either or both of the first and second surfacesand. For instance, the solidified metalcan terminate at each of the first surfaceand the second surface. The solidified metalin the viais in a solid state, also referred to as a solidified metal. As will be appreciated from the description below, during fabrication of the substrate, the metalcan be melted to a molten state to produce a molten metal, for instance in an oven. The molten metalcan flow (e.g., can be pulled) into the viaby capillary action (see), and can be subsequently solidified so as to define the solidified metalshown at. The molten metalcan flow into the viaby capillary action according to Euler's equation. Because the substratedoes not include a protective or sacrificial layer, the molten metalonly enters the viasthat extend through the substrate bodyduring capillary action, and does not fill other vias that are not defined by the substrate body.

In other examples, as shown at, the viascan be alternatively filled by introducing a dry metal powderinto the via, and then subsequently liquifying or melting the metal powdercontained within the viausing any suitable heat source as desired. For instance, the ambient temperature can be increased in the ovenof. Alternatively, inductive inductive/induction heating, such as RF/Eddy currents, can liquify or melt the powder, which causes the metalto melt and subsequently solidify to define the solidified metal(see). The viaofcan include the adhesion layerapplied to the inner surface, and the wetting linerapplied to the adhesion layeras described above. Alternatively, the viacan include the adhesion layerbut not the wetting layer, such that the solidified metalbears directly against the adhesion layer. Alternatively still, the viacan be devoid of each of the adhesion layerand the wetting layer, such that the solidified metalbears directly against the inner surface. In still other examples, as shown in, the substratecan be placed into a bathof molten metal, and removed from the bathsuch that the molten metalon either or both of the first and second surfacesandcan metallize the viasvia capillary action. Alternatively, the substratecan be placed into the bathsuch that the molten metalfills the viawhile the substrate is disposed in the bath. For instance, the molten metalof the bathis disposed on both sides of the viasimultaneously. Alternatively still, the substratecan be placed in the bathsuch that the molten metalis disposed on only one side of the via. The molten metal, the dry metal powder, and thus the solidified metalcan be any one or more of copper, silver, gold, platinum, aluminum, palladium. In some examples, the metal can be a pure metal, meaning that the metal is not alloyed with other metals. In other examples, the metal can be an alloy.

In general, and without being bound by theory, the present inventors have found that the substrate bodymade from one or more materials with high melting points, such as crystalline Si (melting temperature (Tm)=1414 degrees C.), Al2O3 (Tm=2040 degrees C.), glasses such as fused silica (glass transition temperature (Tg)=1200 degrees C.), borosilicate (Tg=525 degrees C.). The substrate body can alternatively be a ceramic among certain ceramics that can receive and successfully tolerate certain molten metals. The term successfully tolerate can mean that the substrate bodydoes not melt or transition or crack during exposure to the molten or liquid metal. Although molten metals are disclosed, this disclosure also contemplates conductive inks and other electrically conductive carbons, metals and alloys that are liquid at ambient temperatures or temperatures not exceeding 475 degrees Celsius. The term “ambient temperature” can refer to a temperature range from approximately 20 degrees Celsius to approximately 40 degrees Celsius.

The term “approximately,” “substantially,” and the like along with derivatives thereof are intended to mean considerable in extent or largely but not necessarily wholly (but can include wholly) that which is specified. As used herein, the term “substantially,” “approximately,” derivatives thereof, and words of similar import, when used to describe a size, shape, orientation, distance, spatial relationship, or other parameter includes the stated size, shape, orientation, distance, spatial relationship, or other parameter, and can also include a range up to 10% more and up to 10% less than the stated parameter, including 5% more and 5% less, including 3% more and 3% less, including 1% more and 1% less.

One method of metallizing the viacan include the step of selecting or providing a substrate bodymade from a first material. The substrate bodyor first material can have a first melting or glass transition temperature (or material melting or glass transition temperature) that is numerically higher, in degrees Celsius, than a second or melting or liquid phase temperature (or metal melting or liquid phase temperature), measured in degrees Celsius, of the metal to be introduced into the via. The metal can be a non-suspension in some examples. The reverse is also true, such that the second melting or liquid phase temperature is less than the first or melting or glass transition temperature. Another aspect or step can include selecting or providing a metal to be introduced into the via, whereby the metal has a second or melting or liquid phase temperature, in degrees Celsius, that is numerically less than a first or melting or glass transition temperature, in degrees Celsius, of the corresponding substrate body. Thus, heating the metal and the substrate bodyto the melting or liquid phase temperature of the metal does not damage the substrate body. In general, the substrate bodyshould not disintegrate or melt when the molten metal or metal alloy is in physical contact with the substrate, or when the substrate bodyand metal are subjected to a temperature sufficient to cause the metal to melt or enter its liquid phase. In this regard, it should be appreciated that at least a portion up to an entirety of the substrate bodycan be heated to a temperature greater than room temperature when the molten metalflows into the via. In some examples, at least a portion up to an entirety of the substrate bodycan be heated to a temperature greater than approximately 120 degrees Celsius room temperature when the molten metalflows into the via.

Referring togenerally, it should be appreciated that the molten metalcan be at a temperature less than the glass transition temperature or melting temperature of the substrate body. For instance, the molten metalcan be at a temperature greater than approximately 90 degrees Celsius but at or below 1000 degrees Celsius, above 150 degrees Celsius but at or below 1000 degrees Celsius, above 250 degrees Celsius but at or below 1000 degrees Celsius, above 350 degrees Celsius but at or below 1000 degrees Celsius, above 100 degrees Celsius but at or below 500 degrees Celsius, above 90 or 100 degrees Celsius but at or below 1500 degrees Celsius, above 250 degrees but at or below 1500 degrees Celsius, and above 350 degrees Celsius but at or below 1500 degrees Celsius. In some example, the molten metalcan flow into the viaat a temperature greater than approximately 280 degrees Celsius but less than the glass transition temperature of the substrate body. In other examples, the temperature of the molten metalcan be in a range from approximately 280 C to approximately 1064 C. In particular, the temperature of the molten metalcan be in a range from approximately 700 C to approximately 1061 C. The molten metaland the powdered metal, and thus the solidified metal, can be devoid of frit, glass frit, alcohol, and isopropyl alcohol. The molten metaland the powdered metal, and thus the solidified metal, can further be devoid of tin or solder flux.

When fabricating the electrically conductive substrate, it is desirable to cause the metalto enter the viasuch that the solidified metaldefines an electrically conductive path between the first surface(or first opening) and the second surface(or second opening). For instance, the solidified metalcan define the electrically conductive path from the first surface(or first opening) to the second surface(or second opening). Thus, in some examples, it is desirable to cause the molten metalto flow all the way through each via, such as from the first via openingto the end of a blind via or to the opposed second opening. A typical contact angle for molten or liquid metals or molten metal alloys on oxide, nitride and carbide substrates is greater than 90 degrees, which results in a negative capillary height. In turn, a negative capillary height impedes the flow of a molten metal/metal alloy into the corresponding via. The present inventors have found that an adhesion layer or linercan be applied to the inner surface, and a second electrically conductive layer or liner, which can define a wetting layer or liner, can be applied to the adhesion layer, to provide a contact angle less than 90 degrees. The metalcan subsequently be inserted into the via.

The adhesion layercan extend along an entirety of the length of the via. Thus, in one example, the adhesion layercan extend from the first surfaceto the second surface. The adhesion layercan electroplated, applied by atomic layer deposition (ALD), chemical vapor deposition (CVD) or physical vapor deposition (PVD). The adhesion layercan be electrically conductive. For instance, the adhesion layercan be made of titanium, either as pure titanium or a titanium alloy. The titanium can be deposited to the inner surfaceusing physical vapor deposition. In other examples, the adhesion layercan be made of tantalum, either as pure tantalum or a tantalum alloy such as tantalum nitride. The tantalum can be deposited to the inner surfaceusing atomic layer deposition. physical vapor deposition. The adhesion layercan be devoid of tin or solder flux as desired. In other examples, the adhesion layercan be electrically nonconductive.

The wetting linercan be applied to the adhesion layer, such that the adhesion layeris disposed between the inner surfaceand the wetting liner. Thus, the adhesion layercan adhere the wetting linerto the inner surface. The adhesion layerand the wetting linercan extend along at least a portion, such as a majority up to an entirety of the length of the via. For instance, the wetting linercan extend from the first surfaceto the second surface. As is described in more detail below, the substrate bodyand/or the wetting linercan define a desirable contact angle with the molten metalto facilitate the capillary action of the molten metalas the molten metaltravels into the via. The wetting linercan be copper, either as pure copper or as a copper alloy. Alternatively, the wetting linercan be gold, either as pure gold or as a gold alloy. Thus, the wetting linercan be the same material as the metalthat defines the electrically conductive path in the via. The wetting linercan be devoid of tin or solder flux in some examples. The wetting linercan be applied to the adhesion layerby electroplating, atomic layer deposition (ALD), chemical vapor deposition (CVD) or physical vapor deposition (PVD). The wetting linercan be electrically non-conductive in some examples as desired. The adhesion layer, and the wetting liner, can be applied onto all exposed surfaces of the substrate body, including the inner surfacesthat define the respective vias, and first and second via openingsand, respectively. Application of the adhesion layerand the wetting linermay also cause some of the adhesion layer material and wetting liner material to be applied to either or both of the first and second surfaces, but can be removed by polishing or alternative method as desired.

As shown in, a wafer or substratecan include a substrate bodyof a first material, such as fused silica for example. The substratecan include at least one via or a plurality of viasthat extend through the substrate body. The viascan be pre-drilled or pre-etched or otherwise pre-formed vias. The viascan be configured as through vias, blind vias, or both that each define a respect empty volume. A through via can extend from the first surfaceof the substrate bodyto the second surface. A blind via can extend from one of the first and second surfacesand, and terminates within the substrate bodyso as to not extend to the other of the first and second surfacesand.

One, two, two or more, three or more, or four or more viascan have high aspect ratios, measured as a ratio of via length divided by a maximum cross-sectional dimension of the vias. Each viacan extend along a central axis along its length. When the viais a through via, the central axis, and thus the length, can extend from the first surfaceto the second surface. The cross-sectional dimension can be measured in a direction perpendicular to the central axis. When the viais substantially cylindrical, the maximum cross-sectional dimension of the viacan be a diameter D of the via. The aspect ratio can be any one of approximately five, approximately six, approximately seven, approximately eight, approximately nine, approximately ten, or any suitable alternative ratio as desired. The viacan define any suitable aspect ratio as desired, it having been found by the present inventors that greater aspect ratios can increase the capillary action of the molten metal as the molten metal flows into the via. A molten metal can undergo increased flow under capillary action into at least one viacan be positioned in the at least one viawith increasing aspect ratios.

The diameter or other cross-sectional dimension can be substantially constant at each of the first openingor the first surfaceand the second openingor the second surface. In examples whereby the viais substantially cylindrical, the diameter or other cross-sectional dimension can be substantially constant from the first openingor the first surfaceto the second openingor the second surface. In other examples, the viacan be hourglass shaped, whereby the diameter or other cross-sectional dimension is less at a location between the first and second surfacesandis less than the diameter or other cross-sectional dimension at either or both of the first and second openingsand, and thus at either or both of the first and second surfacesand.

Viasfabricated into the substrate bodyare typically very small. The length and maximum cross-sectional dimension are measured in um (microns). The viascan have a maximum cross-sectional dimension in a range from approximately 5 μm to approximately 100 μm in diameter. In other examples, the maximum cross-sectional dimension can be in a range from approximately 40 μm to approximately 3 mm. Thus, one or more viascan have a via diameter of approximately 40 um (microns). In another example, the vias can have any diameter in a range from approximately 41 um (microns) to approximately 3000 um (microns). The viascan in a range from approximately 50 μm to approximately 500 μm along a central axis. The substratecan include any number of viasat any suitable density as desired. For instance, the substratecan include a number of viasper square centimeter in the tens, hundreds, or even thousands. Each of the viascan be fabricated in the manner described herein.

The electrically conductive substratecan include the adhesion layerthat is deposited or otherwise applied to the inner surface, and a wetting linerthat is deposited or otherwise applied to the adhesion linerin the manner described above. The adhesion layercan be approximately 5000 Ångstroms thick in one example. The adhesion linercan be a titanium alloy such as titanium-tungsten (TiW). The adhesion linercan be electrically conductive. Next, the wetting layercan be applied to the adhesion linerin the manner described above. In one example, the wetting layercan have a thickness from approximately 1 um to approximately 6 um. The wetting layercan be a layer of copper. Alternatively, the wetting layercan include one or more of silver, gold, platinum, aluminum, palladium, nickel, titanium, chromium, in their pure forms or as alloys thereof. Although optional, the substrate bodycan then be chemically mechanically polished (CMP) to remove the adhesion linerand the wetting layerthat may have been deposited onto the first and second surfacesand. Alternatively, either or both of the first and second surfacesandcan be masked during the application of the adhesion linerand the wetting layer to prevent deposition on to the first and/or second surfacesand.

The substratecan then be pre-heated, such as with an infrared (IR) lamp. A solder flux can be sprayed on the first and second surfacesandif desired. Otherwise, the substratecan be devoid of solder flux or tin. The substratecan then be dipped into a bathof molten metalin the manner described above (see). The molten metalcan be configured in any manner described above, or can alternatively be SAC305, Sn96.5Ag3Cu0.5 liquid solder, which has a lower melting point than the material of the substrate body. It should be appreciated that when the substrateis placed in the bath, the molten metalcan physically contact either or both of the first and second surfacesand, and a quantity of the molten metalof the bathflows into the viastoward the other of the first and second surfacesand.

The molten metalcan be drawn into the at least one viaby capillary action or solely by capillary force or action. In one example, the molten metalcan travel in the viafrom the first surfaceor first openingtoward the second surfaceor second openingvia capillary action. For instance, the molten metalcan travel from the first surfaceor first openingto the second surface or second opening. Alternatively or additionally, the molten metalcan travel in the viafrom the second surfaceor second openingtoward the first surfaceor first openingvia capillary action. For instance, the molten metalcan travel from the second surfaceor second openingto the first surface or first opening. To the extent that a quantity of solidified metalcan remain on either of the first and second surfacesandonce the substrateis removed from the bath, the fabrication method can include the step of removing the excess solidified metalfrom the first and second surfacesand, such as by chemically mechanically polishing (CMP) or any suitable alternative method as desired.

Once the substrateand the re-solidified solder or other metal or metal alloy contained in the at least one viacools, the at least one viacan be filled, in order of decreasing volume, with cooled or solidified molten metal/metal alloy, the second layer, and the adhesion liner. The same process applies to the rest of the plurality of vias.

As shown in, the cooled and solidified metalcan define, in cross-section, a column that extends along a majority length of at least one via, from the first via openingto the second via opening. The column can have a relatively uniform cross-sectional width W along the majority length, which can define a diameter or any suitable alternative cross-sectional dimension. The solidified metalcan extend, from the first via openingtoward the second via opening, into one of at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, and approximately 100% of the distance in the viafrom the first surfaceto the second surface. Alternatively or additionally, the solidified metalcan extend, from the second via openingtoward the first via opening, any one of at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, and approximately 100% of the distance in the viafrom the second surfacetoward the first surface. The solidified metalcan occupy at least 50% of a total volume of the via. Thus, the solidified metalcan form the majority of electrically conductive fill in the at least one via.

In accordance with certain examples, through vias having high aspect ratios, such as high aspect ratio through silicon vias (TSVs) or through glass vias (TGVs) can be filled with a non-porous electrically conductive metalin the molten phase using capillary force in a single, rapid, scalable step. Because capillary forces increase as the via diameter decreases, this method favorably scales with shrinking interposer and chip sizes.

One method of filling the via with the metalwill now be described with respect to. In particular, at least one quantityof the metalin solid form can be placed against (i.e., in physical contact with) either or both of the first and second surfacesandin a position at least partially aligned with at least one of the vias. For instance, the quantitycan be fully aligned with the at least one of the vias. Thus, the at least one quantitycan fully cover at least one of the first openingand the second openingof the respective at least one via. Each quantityof the metalcan be configured as a preformed massof metalsized to cover the respective at least one of the vias. In one example, the preformed massof metalcovers only a respective single via. Each preformed masscan be melted, which causes the metalof the preformed massto flow or be pulled into the viaby capillary action from the respective first and/or second surface toward the other of the first and second surface in the via. In other examples, at least one preformed masscan be sized to cover a respective plurality of the vias, such that when the preformed massis melted, the metalof the preformed mass melts and flows by capillary action into each of the respective plurality of vias.

When the preformed masscovers only one of the openings,of the via, then each preformed masscan have a sufficient quantity of metal to fill the viawith the solidified metalto the extent desired. When first and second preformed massescover the first and second openingsandof the via, the first and second preformed massescan combine to have a sufficient quantity of metalthat fills the via with the solidified metalto the extent desired.

The at least one viacan be pre-coated or uncoated and can define a void that extends fluidly between the two opposed, open endsandof the at least one via. The substratecan include at least one viathat can further include the wetting layerand the adhesion layeras described above. In one example, the substrate bodyand the at least one preformed masscan be heated simultaneously. For instance, the substrate bodyand the at least one preformed mass can be placed in the oven, and the ovencan be heated to a heated temperature greater than the melting temperature of the preformed massand less than the transition temperature and melting temperature of the substrate body. Thus, the heated temperature is sufficient to transition the metalof the preformed massfrom the solid state to the molten state. The resulting molten metalflows into the viaunder capillary action. In particular, the molten metalfrom any preformed massat the first surfaceflows into the viafrom the first surfacetoward or to the second surface. Similarly, the molten metalfrom any preformed massat the second surfaceflows into the viafrom the second surfacetoward or to the first surface. It should thus be appreciated that all preformed massescan be melted simultaneously so as to correspondingly cause metalto flow into the viassimultaneously. The molten metalcan subsequently be cooled to a temperature less than the melting temperature of the metal, which causes the molten metalto solidify and define the solid metalas described above and shown at.

As shown at, the molten metalcan define a first contact angle Θwith respect to the respective first surfaceor second surface. In particular, as the metalis melted to define the molten metal, the molten metalcan tend to form a sphere under surface tension, which can create a contact angle greater than 90. However, as the molten metaltravels along the wetting liner, the molten metal deviates from the spherical shape so as to define the first contact angle Θ, which can be measured as an angle defined by the inner surface of the first surfaceor the second surfaceand a straight line tangent to the molten metalat an interface between an outer surface of the molten metaland the first or second surface,. The term “first” contact angle refers to a location of a contact angle, measured along the first and/or second surface,. It does not necessarily imply that all first contact angles Θare the same. For instance, the first contact angle Θat one side of the molten metalon the first or second surface,can be the same or different than the first contact angle Θat another side of the molten metal on the first or second surface,. Thus, the molten metaloutside of the viais pulled to flow into the viaunder capillary action. The molten metalcan contact the first or second surface,directly prior to flowing into the viain one example. Alternatively, the adhesive layerand wetting linercan be applied to the first and second surfacesandas desired, and subsequently removed by chemically mechanically polishing (CMP).

The molten metalcan further define a second contact angle Θwith respect to the wetting linerin the via. In particular, as the molten metaltravels along the wetting liner, the molten metal deviates from a spherical shape so as to define the second contact angle Θ, which can be measured as an angle defined by the inner surface of the wetting linerand a straight line tangent to the molten metalat an interface between an outer surface of the molten metaland the wetting linerinside the via. The term “second” contact angle refers to a location of a contact angle, measured along the wetting liner of the via. It does not necessarily imply that all second contact angles Θare the same. For instance, the second contact angle Θat one side of the viacan be the same or different than the second contact angle Θat another side of the via. The contact angles Θand Θcan be less than 90 degrees, which creates a positive capillary height that enhances the flow of the molten metalinto the respective via.

In another example, one or more of the preformed massescan be selectively melted without bringing an entirety of the substrate bodyto the melting temperature of the metal. For instance the preformed masscan be subjected to RF waves(see) to induce Eddy currents in the preformed massesand melt the corresponding metal, which thereby causes the resulting molten metalto flow under capillary action into the respective at least one via. The liquid or melted metal/metal alloy preforms or preformed metal/metal alloycan be pulled into the at least one viaby capillary forces and then cooled or allowed to cool as desired.

Referring now to, as another alternative, the preformed masscan be selectively heated or reflowed using an excitation device, source, or method. The excitation devicecan be configured as a laser that directs a laser beamto the preformed mass. One or more laser beamscan be directed to a respective one or more preformed massessimultaneously as desired in order to simultaneously cause molten metalto simultaneously flow into the respective viasunder capillary action. Excitation reflow or laser reflow can be advantageous in situations where it is preferred not melt the metalof the preformed masseswithout heating or baking the entire substrate body, or without simultaneously heating or baking both sidesandof the substrate body.

Thus, a method to fill at least one viain the glass substrate, such as a glass substrate, can include any one or more of the steps of providing the glass substrate, positioning one or more preformed massesonto either or both of the first and second surfacesand. The preformed massescan be placed adjacent a respective one or more of the first and second openingsandwith or without solder flux, such as by a pick and place machine. The method can include the step of selectively applying an excitation device, such as a laser beam, to the preformed massessufficient to cause the solid metalto reach a melting temperature that causes the solid metal to melt and define molten metal, which causes the metal to flow from either or both of the first and second surfacesandtoward the other of the first and second surfacesandunder capillary action. Advantageously, the excitation device or laser beam can melt one or more preformed masseswithout directing the excitation device or laser beam at an entirety of the substrate body. Thus, at least a portion of the substrate bodydoes not receive the excitation device or laser beam in some examples.

Referring again to, methods and apparatus have been described herein for producing the substratehaving a substrate bodyand a plurality of viasthat extend into or through the substrate bodythat have been metalized with a molten metal that has flowed into the via under capillary action. In some examples, the metal of the molten metal was previously a solid metal in contact with the substrate bodythat was then subsequently melted to define the molten metal. Once the viahas been suitably filled with the desired quantity of metal, the metalcan be cooled to produce the solid metal. The method can further include the step of polishing either or both of the first and surfacesand, for instance using CMP, to remove excess of the solidified metalfrom the either or both of the first and second surfacesand.

With continuing reference to, the method can further include the step of applying one or more redistribution layersto either or both of the first and second surfacesandafter the viashave been metallized. The redistribution layerscan be applied so that they are in electrical contact with at least one of the vias. The redistribution layerscan route electrical signals as desired. It should further be appreciated that the substratecan include one or more contact pads that are directly disposed on the first and second surfacesand. The redistribution layersand the contact pads can be made of a different material than the metal. Alternatively the redistribution layersand the contact pads can be made of the same material as the metal. Thus, the substratecan be configured as an interposer that makes electrical contact with complementary electrical devices that are placed in electrical communication with the first and second surfacesandof the substrate, and thus with each other through at least one of the vias. In this regard, the substratecan define an interposer and does not define a semiconductor device.

Referring again to, it is appreciated that the solid metalcan define voids in the via. The viacan include a fill materialthat is introduced into the viasto fill at least some u to all of the voids. The fill materialcan be a polymer in one example. The fill materialcan include or be a glass frit, which can be a lead-free glass frit, a polymer, other suitable material, or any combination thereof. The solid metaland/or the fill materialcan hermetically seal the at least one via.

Any proceeding methods or structure can be incorporated into the preform/preformed embodiments described herein.